Rotary piston machine with splined internal shaft

ABSTRACT

The invention relates to a rotary piston type machine of the type which utilizes a gerotor mechanism for the expansible chambers. In the prior art the ring member of the gerotor normally or often has seven internally extending teeth and holes are normally provided in the seven teeth to accommodate seven screw bolts used for clamping together the casing parts. In the machine hereof the gerotor ring member is clamped between two side disks which in turn are disposed in counterbores of concentric casing collar portions which collar portions are in axially spaced relation to each other when in their clamped positions. Only four screw bolts are utilized for clamping together the casing parts and these bolts are positioned radially externally of the gerotor ring member and the two side disks thereof.

United States Patent [191 Hansen et al.

[ ROTARY PISTON MACHINE WITH SPLINED INTERNAL SHAFT [75] Inventors: Gunnar Lyshoj Hansen, Nordborg; Rolf Christensen, Sonderborg, both of Denmark [73] Assignee: Danfoss A/S, Nordborg, Denmark- [22] Filed: Mar. 21, 1973 [2]] App]. No.: 343,444

[30] Foreign Application Priority Data Apr. 26, 1972 Germany 2220391 52 us. Cl 418/61 B [51] Int. Cl. F04c 17/06 [58] Field of Search 418/61 B, 132, 133

[56] References Cited UNITED STATES PATENTS 3,270,681 9/1966 Charlson 418/61 B 3,385,057 5/1968 Pruvot 418/61 B 1451 July 30, 1974 Primary Exdminer-C. J. Husar Assistant Examiner-Leonard Smith [57] ABSTRACT The invention relates to a rotary piston type machine of the type which utilizes a gerotor mechanism for the expansible chambers. 1n the prior art the ring member of the gerotor normally or often has seven internally extending teeth and holes are normally provided in the seven teeth to accommodate seven screw bolts used for clamping together the casing parts. In the machine hereof the gerotorring member :is clamped between two side disks which in turn are disposed in counterbores of concentric casing collar portions which collar portions are in axially spaced relation to each other when in their clamped positions. Only four screw bolts are utilized for clamping together the casing parts and these bolts are positioned radially externally of the gerotor ring member and the two side disks thereof.

5 Claims, 3 Drawing Figures PATENTEDJULSOIHH SHEET 1 or 2 s i? i? 5% l ROTARY PISTON MACHINE WITH SPLINED INTERNAL SHAFT The invention relates to a rotary pistonmachine having a splined internal shaft and an outer stator, in the form of an'annulus and preferably interposed between side discs, clamping between two housing parts which are urged towards each other by screw-bolts.

In the known arrangements of this kind, the stator,

the clamping housing parts and any side discs present have approximately the same circumferentialdimem sions. The clamping screw-bolts extend through corresponding holes in the outerstator and in the side discs. Each bore is located near the crest of a tooth on the stator. This results in a corresponding reduction in the strength of the stator and in the need for a number of screw-bolts corresponding to the number of teeth on the stator.

The object of the invention is to provide a rotary piston machine of the initially stated kind in which there is greater freedom as regards the arrangementof the clampingscrew bolts.

According to the invention, this object is achieved by the clamping housing parts each being provided with an their associated collars, but will not be pressed outwardly through a gap between the stator and the part adjacent thereto.

It is very advantageous if a side disc carries, in a central bore, a bearing bush on which is mounted a valve disc which is connected to and rotates with-the rotor and which, together with the side disc, formsa distributor valve and is pressed in the axial direction against the side disc. Since the side disc is centred by the centreing collar and in turn carries the valve disc with the aid of the bearing bush, this arrangement results in a distributor valve that is very'precisely centred.

The invention willnow be described in greater detail by reference to a preferred embodiment illustrated in the drawing, in which:

FIG. 1 shows a longitudinal section through a rotary piston machine in accordance with the invention,

FIG. 2 is an end view from the right, a square flange being shown at the left-hand side and a circular one at the right-hand side, and FIG. is a transverse section taken on line Ill-III of FIG. 1.

axially extending centreing collar which surrounds a cylindrical peripheral zone of the stator, and one of the side discs if present, and by the screw-bolts being located substantially externally of this peripheral zone.

In this construction the stator is centred independently of the clamping screw-bolts. The screw-bolts can be placedin any position in relation to the teeth-Excellent centreing is achieved since only two centreing surfaces between each clamping housing part and the stator and extending concentrically with the axis'of the machine are present. In otherwise similar conditions, the stator may have a smaller diameter and/or greater strength.

In some cases it is advantageous if the cylindrical periphery of thestator carries a flange of smaller thickness through which the screw-bolts pass with clearance. This flange bridges the gapbetween the'centreing collars of the two clamping housing parts and increases the strength and rigidity of the stator.

. A particularly great advantage of this arrangement is seen to reside in the fact thatthe number of screw-bolts may be smaller than the number of teeth on the stator. Whereas in the case of a stator having seven teeth, it has hitherto been necessary to provide seven screwbolts, it is now possible to employ a smaller number of screw-bolts.

In particular, four screw-bolts can be provided at the corners of a rectangle or square. The screw-bolts can then be disposed substantially outwardly of the periphery of the stator without this resulting in any increase in the height and width of the machine.

The periphery of the flange preferably matches the crosssectional form of the clamping housing parts. ln this connection considerable advantage accrues if at least one clamping housing part is of substantially square cross-section and if the screw-bolts are disposed at the corners of the square.

In a preferred arrangement, the end-walls of the stator or that end-wall of each of the side discs that is presented to the stator contain a groove which extends along the periphery and in which a sealing ring is fitted.

Each of these sealing rings is likewise enclosed within .If the illustrated machine is to be used as a motor, then pressurized fluid is supplied to it selectively through one of the ports 1 or and low-pressure fluid is discharged through the other port 2 or 1, whilst driving power is taken from a shaft 3. If a driving torque is applied to the shaft' 3, the machine can also be used as a pump.

The housing has two clamping parts 4 and 5 between which are positioned an outer stator 6 and two side discs 7 and 8. When the two clamping housing parts 4 and 5 are drawn together with the aid of four clamping screw-bolts 9, the end faces 10 and 11 of these housing parts act on the side discs and the stator and clamp these components firmly together. The stator 6 has a cylindrical periphery 12. The diameter of the stator and the diameters of the side discs 7 and 8 are the same as one another. The part 4 has a centreing collar 13 which extends over the periphery of the side disc 7 and the adjacent portion of the periphery 12 of the stator in a sliding fit. The housing part 5 has a centreing collar 14 which surrounds the periphery of the side disc 8 and the adjacent periphery 12 of the stator, likewise in a sliding fit. The peripheral portion 12 of the stator carries a flange 15 of smaller width than the stator; this flange bridges the gap between the centreing collars 13 and 14 and increases the strength of the stator 6. The shanks of the clamping screw-bolts 9 lie outwardly of the cylindrical periphery 12 of the stator 6. Bores or recesses 16are formed in the flange 15 to accommodate the shanks of the screw-bolts.

The housing part4 is closed at one end by a coverplate 17. The housing part carries a double roller hearing 18 with the help of which is mounted a hollow portion 19 of the shaft 3. In meshing engagement with a toothed portion 20 of this hollow shaft portion 19 is a toothed head 21 of a first universal-joint shaft 22, the opposite toothed head 23 of which meshes with a toothed portion 24 of a rotor 25 which takes the form of a toothed ring. Together with the teeth 26 of the stator, the teeth of this rotor form displacement chambers 27 which here take the form of cylindrical insets and which, with the aid of a distributor valve, are connected in the correct sequence to the ports 1 and 2 respectively.

For the purpose of forming the distributor valve, the

side disc 8 carries, in an internal bore, a bearing bush 3 28 on which is mounted a rotating valve disc 29. This valve disc 29 is connected to the rotor by way of a second universal-joint shaft 30 and rotates with the-rotor, a first toothed head 31 of this universal-joint shaft meshing with the toothed portion 24 of the rotor, and a second toothed head 32 with a toothed portion 33 of the valve disc 29. A plunger 34 presses the valve disc 29 tightly against the side disc 8. A central stud 35 performs the function of an axial stop for the universaljoint shaft 30and prevents axial loads from being transmitted to the valve disc 29 or to the plunger 34.

The side disc 8 has axially extending passages 36 each of which is associated with the base of a tooth of the stator 6. The precise angular position is achieved by means of a pin 53. The valve disc 29 has alternately valve openings 37 which communicate with the port 1, and valve openings 38 which communicate with the port 2. The number of valve openings 37 and 38 is in each case equal to the number of teeth on the rotor 25. A passage 39 in the valve disc 29 extends from each valve opening 37 to an annular groove 40. This groove communicates with an annular chamber 42 by way of passages 41 in the pressure plate 34, the number of which passages 41 corresponds to the number of axially extending passages 36. The annular chamber 42 is formed between the clamping housing part 5 and the plunger-34; it communicates directly with the port ll. Each of the valve openings 38 communicates by way of an inclined passage 43 with an annular chamber 44 which surrounds the valve disc 29. This annular chamber communicates directly with the port 2.

The plunger 34 is guided on two concentric surfaces 45 and 46 and is prevented from rotating by a peg 47. The plunger is pressed in the axial direction against the valve disc 29 by one or more springs 48 and by the pressure obtaining in the annular chamber 42 and in the annular gap 54 associated with the annular chamber 44, so that the valve disc 29 is pressed tightly against the side disc 8.

That end face of each of the side discs 7 and 8 that is presented to the stator 6 has a groove 49 and 50 respectively, each groove extending from the circumference of the disc, and a sealing ring 51 and 52 respectively being inserted in each groove. These sealing rings prevent pressurized fluid from escaping across the interfaces between the stator 6 and the side discs 7 and 8; the sealing rings themselves, however, cannot be pressed outwardly by the fluid pressure.

We claim:

1. A rotary piston machine comprising a casing assembly having concentric collar portions in axially spaced relation to each other, said collar portions being formed with bores and counterbores, a pair of side disks disposed respectively in said counterbores and being recessed relative to the free ends of said collars, a stator disk disposed between and in abutting engagement to said side disks, said collars being in axially overlapping relation to said stator disk with the inside diameters of said collar portions and the outside diameters of said disks having the same nominal diameter, and screw bolts for clamping together said casing assembly, said screw bolts being positioned radially externally of said nominal diameter.

2. A rotary piston machine according to claim 1 wherein said stator disk includes a radially extending flange portion in axially spaced relation to said collar portions.

3. A rotary piston machine according to claim 1 wherein four of said screw bolts are used.

4. A rotary piston machine according to claim 1 wherein at least one of said collar portions has a generally rectangularly shaped outer periphery.

5. A rotary piston machine according to claim 2 wherein said flange portion has a generally rectangularly shaped outer periphery.

l i= =k 

1. A rotary piston machine comprising a casing assembly having concentric collar portions in axially spaced relation to each other, said collar portions being formed with bores and counterbores, a pair of side disks disposed respectively in said counterbores and being recessed relative to the free ends of said collars, a stator disk disposed between and in abutting engagement to said side disks, said collars being in axially overlapping relation to said stator disk with the inside diameters of said collar portions and the outside diameters of said disks having the same nominal diameter, and screw bolts for clamping together said casing assembly, said screw bolts being positioned radially externally of said nominal diameter.
 2. A rotary piston machine according to claim 1 wherein said stator disk includes a radially extending flange portion in axially spaced relation to said collar portions.
 3. A rotary piston machine according to claim 1 wherein four of said screw bolts are used.
 4. A rotary piston machine according to claim 1 wherein at least one of said collar portions has a generally rectangularly shaped outer periphery.
 5. A rotary piston machine according to claim 2 wherein said flange portion has a generally rectangularly shaped outer periphery. 